Thermostatic control mechanism



May 9, 1950 R. o. WARNER THERMOSTATIC CONTROL MECHANISM 2 Sheets-Sheet 1 Filed Feb. 23, 1946 INVENTOR. FZdfii 0. l4zrl7e/r BY y 9, 1950 R. o. WARNER 2,507,071

THERMOSTATIC CONTROL MECHANISM Filed Feb. 23, 1946 2 Sheets-Sheet 2 INVENTOR.

Patented May 9, 1950 UNITED STATES PATENT OFFICE THERMOSTATIC CONTROL MECHANISM Roland 0. Warner, Bloomington, Ill., assignor to Eureka Williams Corporation, Detroit, Mich., a corporation of Michigan Application February 23, 1946, Serial No. 649,610

1 Claim. 1

This invention relates to thermostatic control mechanisms and has particular reference to mechanisms for use in connection with irons of the cordless type embodying certain improve ments over the construction disclosed and claimed in the patents to Beach, No. 2,151,888, issued March 25, 1939, No. 2,181,042, issued November 21, 1939, and the patent to Chereton, No. 2,284,132, issued May 26, 1942.

Ironing devices of this type comprise a base or stand to which a current conducting cord is connected, an iron having an electric resistance heating element therein and adapted to be arranged on the stand, the stand and iron having contacts which are engaged when the iron is on the stand so as to close the circuit through the heating element, a switch for controlling such circuit and a thermostat on the base and arranged to engage the sole plate of the iron when the same is on the stand, such thermostat being operative to open and close such switch so as to control the supply of current to the heating element in the iron when the iron is on the stand and in accordance with the temperature of the sole plate of the iron.

In the constructions disclosed in the aforesaid patents, the contacts and the thermostat form the support for the iron on the stand. In irons made according to the construction shown in the Chereton patent, difficulty has been experienced in obtaining a good thermal conducting path between the thermostat and the sole plate of the iron, due principally to the fact that the plane in which the sole plate was supported did not correspond with the plane of the supporting surface afforded by the thermostatic element.

This has prevented the thermostat from responding efiiciently to the temperature changes in the sole plate and hence has interfered with the accurate control of the temperature of the iron.

According to the present invention, this difficulty has been obviated by loosely supporting the thermostatic element so that its sole plate engaging surface may be adjusted to that of the surface of the sole plate and by providing a magnet for holding the thermostat against the sole plate so as to obtain surface contact therebetween, as distinguished from line or point contact which is obtained in the construction shown in the Chereton patent.

The principal object of the invention, therefore, is to provide an iron or the aforesaid type in which means are provided to insure good surface contact between the thermostat and the sole plate of the iron.

Other and further objects of the invention will be apparent from the following description and claim and will be understood by reference to the accompanying drawings, of which there are two sheets, which, by way or illustration, show a preferred embodiment and the principles thereof and what I now consider to be the best mode in which I have contemplated applying those prin ciples. Other embodiments of the invention embodying the same or equivalent principles may be used and structural changes may be made as desired by those skilled in the art without departing from the present invention and the purview of the appended claim. I also contemplate that of the several different features of my invention, certain ones thereof may be advantageously employed in some applications separate and apart from the remainder of the features.

In the drawings:

Fig. 1 is an elevational View of an ironing apparatus embodying the invention;

' Fig. 2 is an enlarged fragmentary sectional view taken generally along the line 2-2 of Fig, 3;

Fig. 3 is a plan view of the base or stand; and

Fig. i is a diagrammatic view of an electric circuit which may be employed in practicing the invention.

As shown in the drawings, an ironing apparatus embodying the invention comprises a stand it and a hand iron l2. The stand or base It is provided with two electric contacts i4 and a thermostatic support 16 which form a threepoint support for the iron on the stand. A current conducting cord [8 is connected to the stand It and is electrically connected to the contacts it under the control of a switch 26 (Fig. 2).

The iron [2 has two contacts 22, One of which is shown in Fig. 1, which are arranged to engage the contacts 14 when the iron is on the stand so I as to support the iron and in addition to put the electric resistance heating element in the iron [2 in an electrical circuit under the control of the switch 20. For further particulars of the construction and operation of irons of this type, reference may be had to the foregoing patents and particularly to the patent of Chereton.

' The thermostat support and assembly It comprises a cup-shaped casing 24, an encircling band 26 fixed thereto, a thermally responsive or bimetallic element 28, a laminated core 353, a spool or bobbin 32, a coil 35, a pair of hard brass washers 3E and 38, and an adjustable screw 40.

The casing 24 forms the housing of the electromagnet and has the coil 34, the spool 32 and the core 30 operatively secured therein. The hard brass washers 36 and 38 are secured to the upper end of the core 30 and within the open top of the casing 24 to close the same. The bimetallic element 28 includes a horizontally extending portion 42 which is clamped between the washers 36 and 38 and extends through a slot in the casing 24 just above the band 26. The horizontal portion of the bimetallic element 28 is securely fixed by the washers 36 and 38 and the casing 24. The vertically extending portion of the bimetallic element '28 is adapted to be deflected to the right (Fig. 2). The screw 40 carried by the movable end of the bimetallic member 281 arranged to react through a slidable cam member 44 on a switch actuating plunger 46 for opening the contacts of the switch 20. This feature is fully dis closed in the aforesaid Chereton pate nt. The switch 29 may be of any conventional or desired construction and include contaetsi which are" nor mally closed. The switch contacts are arranged to be opened by movement of the switch actuating plunger 46 to the right (Big. 2).

The casing 24 is loosely arranged in ahole in the wall 50 of the base II]. The band 261s arranged to rest on the rim of the wall 50 defining the opening through. which thecasing 24 dependsso as to support the casing 24' on. the base. A guard 52 surrounds that portion of the thermostatic assembly [6 which projects above the wall 553. However, the upper fiat surface 54. or the washer 3 iis arranged above the top-of the guard 52 and forms a supporting. surface for the sole plate 56 of the iron.

Reference may now be had to: Fig. 4 wherein the. circuit of the standand the switch actuatingn iechanism is diagrammatically illustrated. As shown in this view, the movable end 29 of the biemetallic element 28 is arranged to react through the member 44 and the switch actuating plunger 46' to open the contactsof the switch 20 whenthe a how much misalignment there is between the plane of the surface of the sole plate of the iron and the plane of the surface 54; of the thermostat assembly it when the assembly 16 is supported upon the wall 58 by the band 26. The loose mounting of the thermostat assembly [6 and the electromagnetic means for shifting the same so as to bring the surface 54 into good surface engagement with the surface of the sole plate will act tocompensate for such misalignment so that a good thermal path may be provided between thesolenlate of the iron and the bimetallic eleiron becomes heated tothe condition for which the th rmostatically controlled switch. is set by the. adjustable knob 45 Another. switch [illv is provided for controlling thecircuit through the coil, 3,6 of theelectromagnet. member. 62 movable with the member 45 is arranged to open the contacts of the switch 6U simultaneously withthe; opening of the contacts of the switchv 20. When the thermostat coolsdown, thelcontactsof both. switches would closesimultaneously.

The current conductorsfid for the coil 34: are connected to the current conductors l'8iin parallel with the contacts is so that the coil. 3}: will be. energ zedwhenever: the circuitthrough the heats ing element of the iron is closed; The energizing of the. coil 34 will draw the thermostat assemblyt5 up against the surface 56 of the sole plate-.55

of the iron and so that the surface 54. Willseat against the surfacedfi; of thesole plate seas to; establisha good thermal path between the sole;

plate 55 and the bimetallic element. 28-.

The bobbin or spool 32 preferably isiiormed of. steatite, while thesole plate 55; of the ironwill;

haveto be formed of ironor other material have ing magnetic properties.

When the bimetallic element 28 opens the least apart ofv the-band, 26 will engage the wall}- o l th as in ord tosupn r he ss mbly and the frontportion oftheiron. However,

when the switches. ziiand 50,1 open, the contact,

etween th su ac s. 541 a 56' may c an rom.

asurfacecontact toa line contact.

The. aim-p nt of. h f neof th h rmostat a semb y it wh ch. kes: p ace; Will depend upon.

ment '28 when the coil 34 is energized.

In addition to the particular circuit illustrated for controlling the coil of the electromagnet, other circuits might be employed. The guard 52 will engage the band 26 and function-to separate the assembly it from the-iron when and if'the iron is taken from the stand when the coil 34 is energized. The electromagnet may be of the shaded poletype and? have a very low amperage, say, of the order: of one-tenth of an ampere so that it will be possible readily to lift the iron from the stand without having to pull the stand away from the iron.

I also contemplate that the guard 52 may be formed so as to projectslightly above the surface 54 so that the: guard 52 would form the support for the iron and the thermostat would be elec tromagnetically brought into engagement with the sole plate: surface when the circuit through the heating element: of the iron was closed, or when-the iron is on the stand.

While I have illustrated and described a preferred embodiment of. my invention,- it is under stood thatv this is capable of modification .and I- therefore do not wish to be limited to the precise details set forth-butdesireto avail-myself of such changes and alterations which fall within thepurview of the following claim.

I claim:

Thermostatic control mechanism'for an elec-. trically. heated device whose temperature is to be controlled, com-prising abase, a control unit loosely mountedv on saidbase andhaving a planu-- lar surface forming a support forengagement with a plane surfaceoi saiddeviceior supporting said device, a thermally responsive element secured to said controlunit adjacent to and in intimate heat. conducting relation with said planular surface, a switch controlling member mountedfor movement in response to deflection of said thermally responsive element for operating a switch which controls the circuit of the means- 1 for heatingsaid device, and means for positionings'aid control unit so that said planular surfacethereof is parallelto and in engagement with:

said plane surface of said' device when said device is supported by said; support,v said, means comprising an. electromagnet secured to and movable-with said-thermally responsive element.

ROLAND O. WARNER.

REFERENCES CITED The following referencesare of-reeordin th file of thisv patent:

UNITED STATES PATENTS N m er Na e D t 1,135,389 Moore Apr. 13, 1915 2,284,132 Chereton May 26, 1942 2;2'8 8',51 0" Brannon, June 30, 1942 

